How can renewable energy be reliably integrated into the power system? In Waldkappel, a new battery storage facility demonstrates how modern storage solutions create flexibility and support grid stability. Arup supported the project as an independent technical partner and ensured the quality- and schedule-compliant delivery of design, construction, and commissioning.

Waldkappel is a small town in a rural region in northern Hesse and, since the completion of the new battery storage facility, has become an important location for Germany’s energy transition. The plant was successfully commissioned in March 2026. Built on a previously undeveloped site, the facility covers approximately 2,000 m² - roughly a third of the size of a football pitch.

Battery energy storage systems (BESS) help integrate renewable energy efficiently into the power system while maintaining grid stability. As the share of renewable energy increases, balancing electricity generation and demand becomes more challenging. Battery storage systems play a crucial role by storing electricity when wind and solar generation exceeds demand and releasing it when demand rises or generation decreases.

With a capacity of around 16 MW and a storage capacity of more than 33 MWh, the facility can store enough energy to supply nearly 10,000 two-person households for one night. At the same time, the system can deliver its full output for more than two hours.

Innovative concept and technical implementation

The battery system is based on advanced lithium-ion technology and has a modular design. A key feature of the project is its construction approach: instead of using conventional container solutions, the battery units are installed in pre-assembled racks mounted on steel frames. This significantly reduced on-site installation time while increasing flexibility and ease of maintenance. Each module is equipped with its own safety and thermal management systems, ensuring reliable and safe operation. Close proximity to the local substation enables efficient grid connection and minimises transmission losses.

A group of large solar panels.

Battery storage systems are a key component for a secure, climate-friendly and independent energy supply. View of the system in Waldkappel.

Fast delivery and international collaboration

The project was completed within approximately eight months, highlighting the increasing speed and maturity of such modern storage developments. The facility was developed and built by ABO Energy, which has extensive experience in delivering battery storage projects. Globally, ABO Energy is currently developing storage projects with a total capacity of around 4 GW. Prior to construction, the project was sold to Field, an international developer, investor and operator of battery storage systems. Field is building a Europe-wide portfolio of battery storage systems and a platform for flexible energy infrastructure.

Independent technical support

Our energy infrastructure experts supported the project as an independent technical partner (Owner’s Engineer) throughout its entire lifecycle, from the start of construction to final handover.

Owner’s Engineering is becoming increasingly important in the renewable energy sector as projects grow ever more complex, capital-intensive and heavily regulated. The integration of various technologies such as wind, solar and storage, as well as increasing requirements for grid connections and system stability, significantly increase interface and project risks. In this environment, owner’s engineering ensures, through independent technical advice and comprehensive project support, that risks are identified at an early stage, quality is guaranteed, and projects are delivered on time and cost-effectively.

For the battery storage facility in Waldkappel, the Energy Infrastructure Team from our Berlin and Frankfurt offices coordinated the interfaces between the project stakeholders, monitored construction progress and ensured that key project milestones were met. In addition, we verified grid compliance and the fulfilment of performance requirements, and developed the commissioning and testing plan, the implementation of which was closely monitored.

During commissioning, our experts monitored key tests and ensured that all agreed performance parameters were met. In addition, the health and safety documentation and as-built records were reviewed to ensure a fully compliant and risk-minimised project.

Supporting the energy transition

As one of the larger stand-alone battery storage projects in Germany, Waldkappel demonstrates how quickly and efficiently flexible energy solutions can be delivered today. The project makes an important contribution to a stable, climate-friendly, and independent energy supply in Europe.

Images: © Arup, © ABO Energy (top image)

Waldkappel is a key milestone for Field in Germany and marks the beginning of building our German battery storage platform, with further projects to follow at strategically important grid locations on the extra-high voltage level. As our first project in the German market, it demonstrates how flexible storage solutions can make a significant contribution to security of supply, grid stability, and the successful integration of renewable energy.

The technical complexity of modern battery storage projects demands the highest standards in design, construction, and commissioning. Arup supported us as independent Owner’s Engineer in consistently implementing these standards and delivering the project with a strong focus on quality, safety, and long-term performance.

Philip Hainbach

General Manager Germany, Field Germany